The difference between spring sealed safety valve and spring unsealed safety valve is as follows.

According to the different discharge methods and media types, spring safety valves can be divided into three types: fully closed safety valves, semi-closed safety valves and open safety valves.

1. Fully enclosed safety valve. When the fully enclosed safety valve exhausts, all the gas is exhausted through the exhaust pipe, and the medium cannot be leaked. It is mainly used for containers or pressure pipelines with toxic, flammable and explosive gases as the medium.

2. Semi-closed safety valve. Part of the gas discharged from the semi-closed safety valve is discharged through the exhaust pipe at the outlet of the safety valve, and part of it leaks from the gap between the valve cover and the valve stem, which is mostly used in containers with gas or liquid as the medium that will not pollute the environment.

3. Non-enclosed safety valve. The valve cover of the non-enclosed safety valve is opened, which makes the spring cavity communicate with the atmosphere, which is beneficial to reduce the temperature of the spring. It is mainly suitable for containers with steam as the medium and high-temperature gases that do not pollute the atmosphere.

Small low-pressure safety valves are easy to close, but large, high-pressure and long-stroke valves are difficult to close, so closing is not practical.